Update to TJNAF E-03-109: Spin Asymmetries on the Nucleon Experiment - SANE

This document is an update on TJNAF E-03-109, the Spin Asymmetries on the Nucleon Experiment SANE, conditionally approved in June 2003 by PAC24 for 27 days of beam in Hall C. Our collaboration has been working for the past three years preparing the detector elements, polarized target and auxiliary systems to be ready for installation and data taking in the first half of 2008. SANE is a measurement of the proton spin structure function g2 and spin asymmetry A1 over a broad range of the Bjorken scaling variable x from 0.3 to 0.8, for fourmomentum transfers from 2.5 GeV to 6.5 GeV. The experiment will measure inclusive double spin asymmetries using CEBAF polarized electron beams of about 4.8 and 6 GeV energies, scattered off the UVA solid polarized NH3 target. The scattered electrons will be detected in the novel, large acceptance non-magnetic detector BETA (Big Electron Telescope Array), consisting of a forward tracking hodoscope (new in this update), a threshold Cherenkov detector, a Lucite tracking hodoscope and the BigCal electromagnetic calorimeter. Experimental asymmetries will be measured for the configurations of parallel beam and target spins, and target spin at 80 relative to the beam, from which we will obtain the physics spin asymmetries A1 and A2, and the spin structure functions, with minimal external input in the form of the unpolarized structure functions R and F1. In this document we give only a brief review of the status of the proton transverse spin structure function, and concentrate on progress reports on the construction of BETA and related calibration plans, collaboration status and beam request. More extensive discussion of the physics motivation and details of the detector performance are given in the original proposal, which is part of this submission.